The present invention relates to a pneumatic tire suitable for use throughout all seasons. To be more specific, the present invention relates to a pneumatic tire having improved lateral sliding resistance and traction on snow as well as improved resistance to uneven wear.
An all-season pneumatic tire is required to have excellent resistance to uneven wear as well as to securely have sufficient lateral sliding resistance and traction on snow in the event of snowfall.
A conventional tread pattern employed in the all-season tire includes plural circumferential main grooves which are formed in the tread portion and each of which extends in the tire-circumferential direction. The plural circumferential main grooves define plural columns of land areas in the tread portion. The land areas have plural lug grooves each of which extends in the tire-width direction and plural sipes each of which also extends in the tire-width direction (see, for example, Japanese patent application Kokai publications No. 6-55913, No. 2002-67623, and No. 2007-230251.)
The lug grooves extending in the tire-width direction are effective in securing traction on snow. Assigning a wider part of the tread portion to lug grooves, however, lowers down the tread stiffness and thus lowers down its resistance to uneven wear. Besides, such assignment makes the tire more prone to lateral sliding on snow. Accordingly, it is difficult to provide an all-season tire with both improved lateral sliding resistance and improved traction on snow as well as with secured excellent resistance to uneven wear.